Souders

Fig. 24. Souders load diagram for capacity limit determination for four stmctured packiags of the Sul2er-MeUapak type. The soHd lines represent the capacity limits of the respective packiags as defiaed by a pressure drop of 1.2 kPa/m (A) 125 Y (B) 250Y (C) 350Y (D) 500 Y. Flooding rates are about...

W. E. Souder, ManagingNew Product Innovations, Lexiagton Books, Lexiagton, Mass., 1987, pp. 239—244. 

The term in equation 42 is called a Souders-Brown capacity parameter and is based on the tendency of the upflowing vapor to entrain Hquid with it to the plate above. The term E in equation 43 is called an E-factor. and E to be meaningful the cross-sectional area to which they apply must be specified. The capacity parameter is usually based on the total column cross section minus the area blocked for vapor flow by the downcomer(s). Eor the E-factor, typical operating ranges for sieve plate columns are... 

The heating surface usually determines the evaporator cost and the vapor head the space requirements. The vapor—Hquid separator must have enough horizontal plan area to allow the bulk of the initial entrainment to settle back against the rising flow of vapor and enough height to smooth out variations ia vapor velocity and to prevent splashing directly iato the vapor outlet. Separators are usually sized on the basis of the Souders-Brown expression ... 

Entrainment Flooding The early work of Souders and Brown [Ind. Eng. Chem., 26, 98 (1934)] based on a force balance on an average suspended droplet of hquid led to the definition of a capacity parameter C,i, ... 

Katz (R-16) also siwdied wave-plate impingement separators (Fig. 14-Il0b) made up of 90° formed arcs with an 11.1-mm (0.44-iu) radius auda 3.8-mm (0.15-iu) clearance between sheets. The pressure drop is a function of system geometiy. The pressure drop for Katz s system and collection efficiency for seven waves are shown in Fig. 14-111. Katz used the Souders-Brown expression to define a design velocity for the gas between the waves ... 

The Souders-Brown correlation considers entrainment as the controlling factor. For high liquid loading situations and final design, complete tray hydraulic calculations are required. 

Ludwig- states that the Souders-Brown method appears to be conservative for a pressure range of 5 to 250psig allowing W to be multiplied by 1.05 to 1.15 if judgment and caution are exercised. 

C = Souders-Brown maximum allowable mass velocity factor... 

W = Souders-Brown maximum allowable mass velocity, lbs/(ft cross section) (hr)... 

Souders-Brown. The Souders-Brown method (References 1, 2) is based on bubble caps, but is handy for modem trays since the effect of surface tension can be evaluated and factors are included to compare various fractionator and absorber services. These same factors may be found to apply for comparing the services when using valve or sieve trays. A copy of the Souders-Brown C factor chart is shown in Reference 2. 

S = Surface tension, dynes/cm for Souders-Brown correlation or allowable stress, psi for vessel thickness calculation... 

The Souders-Brown [67] empirically correlated maximum allowable mass velocity is represented in Figure 8-82 for C Factor determination, and in Figure 8-83 for solution of the relation ... 

Figure 8-82. C factors for column diameter using bubble cap trays. Adapted by permission, The American Chemical Society, Souders, M., Jr., and Brown, G. G. Ind. and Eng. Cham. V. 26 (1934), p. 98, all rights reserved.

The tower diameter may be calculated for first approximation by the Souders-Brown method however, this has been found to be conservative, since it is based on no liquid entrainment between trays. Actually, some entrainment can be tolerated at negligible loss in efficiency or capacity. 

Most studies have used the Souders-Brown [67] droplet settling velocity concept to relate entrainment flooding. In this mechanism, flooding develops due to a sufficiently high upward vapor velocity through the cross-section of the net area of the column to suspend droplets, and is expressed as the Souders-Brown flooding constant, Csb> [94, 183, 184]. 

For sieve trays Kister s [94, 184] final correlation is for the Souders-Brown flooding coefficient and is essentially independent of pressure. The Kister and Haas correlation [94] [184]... 

A tower diameter is selected based on Souders-Brown (20-50 percent conservative, usually) or Hunt s relation, Equation 8-250. 

Estimated Tower Diameter Souders-Brown method W = C[p,(pi.-pv)]i/2... 

Establish a tower design diameter using the Souders-Brown method or the relation of Hunt, both given previously. 

Souders-Brown, Figure 8-83 at top tray conditions, which are limiting. 

---